CN115021073A - High-power silicon-based semiconductor laser based on apodized grating - Google Patents
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Abstract
The invention relates to a high-power silicon-based semiconductor laser based on apodized grating, which comprises: the quantum well active region comprises a substrate, a buried oxide layer, a waveguide layer, an auxiliary bonding layer, a spacing layer, a cladding layer, a quantum well active region, a top cladding layer, an ohmic contact layer, a P-type electrode and an N-type electrode; an apodization grating is etched in the waveguide layer along the cavity length direction of the resonant cavity; according to the invention, through the design of the apodization grating, the photon density at two ends of the laser cavity has asymmetry, the output light power and the utilization efficiency are obviously improved, and the problem of low output light power/efficiency of the lambda/4 phase-shift laser is effectively solved while the stable single-mode output is ensured. Compared with a lambda/4 phase-shift laser, the resonant cavity based on the apodized grating has more gentle intra-cavity optical field distribution, thereby solving the influence of spatial hole burning of the lambda/4 phase-shift laser and obtaining better laser performance.
Description
Technical Field
The invention relates to a high-power silicon-based semiconductor laser based on apodized gratings, belonging to the technical field of photoelectrons.
Background
With the application of the silicon photonic integrated technology in the fields of high-speed optical communication, big data, high-efficiency calculation and the like, the realization of the high-efficiency silicon photonic integrated light source becomes the focus of attention of people. Since silicon is an indirect band gap semiconductor material, free carrier absorption, auger recombination and indirect recombination effects exist, the light radiation efficiency is extremely low, and the silicon is difficult to prepare into a laser light source. At present, the wafer bonding technology is utilized to adhere a direct band gap III-V group semiconductor gain material on a Silicon On Insulator (SOI) waveguide, so that the advantages of high refractive index difference of the SOI material and high gain of the III-V group material can be combined, and the method becomes one of the mainstream schemes for manufacturing a silicon-based laser.
Distributed feedback lasers (DFB-LDs) are commonly used in III-V/SOI hybrid integrated platforms because they can achieve stable single mode output over a certain current range and temperature range. In a general DFB laser with a uniform grating, when the reflectivity of the cavity surfaces at both ends of the laser is 0, two longitudinal modes are present at both sides of the bragg wavelength, and therefore, single-mode output cannot be realized. In the traditional III-V family DFB laser, the reflection and random phase of the end face can be introduced in a mode of coating films at two ends of a cavity, so that the problem of mode combination is eliminated to a certain extent, and the single-mode output of the laser is realized. However, when applied to III-V/SOI hybrid integration, it is difficult to cut and film the laser at the end facet, and therefore silicon-based III-V DFB lasers typically achieve single mode output by introducing a quarter wavelength (λ/4) phase shift region in the center of the cavity. The lambda/4 phase-shift laser has the lowest threshold gain at the Bragg wavelength, can form stable single-mode output, and can greatly reduce the manufacturing difficulty of the grating compared with a III-V group DFB laser by benefiting from a mature CMOS (Complementary Metal Oxide Semiconductor) process. However, due to the symmetry of the cavity, the output powers of light at the two ends of the cavity are equal, and only the output light at one end can be utilized, which results in lower output power and utilization efficiency of the laser, and the optical field in the cavity of the λ/4 phase-shifted laser is mostly concentrated at the center of the cavity, which is easy to cause a severe longitudinal spatial hole burning effect, thereby limiting the performance of the laser to a certain extent.
Disclosure of Invention
The invention adopts the apodization grating, so that the light emitted from the two ends of the resonant cavity has asymmetry, the output light power and the utilization efficiency are obviously improved, and the problems of low output light power and low utilization efficiency of the lambda/4 phase-shift laser are effectively solved while the stable single-mode output is ensured.
Compared with a lambda/4 phase-shift laser, the laser resonant cavity has more gentle intra-cavity optical field distribution, the problem of spatial hole burning of the lambda/4 phase-shift laser can be effectively reduced, and better laser performance is obtained.
Interpretation of terms:
1. the grating coupling coefficient and the grating periodic corrugated structure can enable distributed mutual coupling to be generated between forward waves and backward waves which are independently transmitted along the cavity length direction, the grating coupling coefficient can represent the feedback strength of a grating, namely the coupling strength between forward light and backward light, and is a critical parameter of the DFB laser, and the expression is as follows:
wherein D represents the duty cycle,
denotes the effective refractive index, λ, of the high and low refractive index portions of the grating in the same period 0 Is the bragg wavelength.
2. An effective index, the effective index describing the amount of phase delay per unit length in the waveguide relative to phase delay per unit length in vacuum, defined as n eff ＝β/k 0 . Wherein, β refers to the propagation constant of the optical wave, and is described as the phase change of the light in the medium or waveguide in unit distance of propagation; k is a radical of 0 Is the vacuum wave number.
3. The molecular bonding technique of silicon dioxide dielectric layer is through SiO 2 The dielectric layer is used as a molecular bonding technology of a bonding interface.
The main principle of the bonding technology is that a III-V direct band gap semiconductor material is adhered above an SOI silicon waveguide through the bonding technology, the problem of lattice mismatching of heteroepitaxial growth can be avoided, and the method is simple in process and high in integration level, so that the method has a good application prospect. According to different bonding materials, four different bonding technologies can be utilized to prepare a hybrid integrated single-mode silicon-based laser for silicon optical interconnection: flip-chip bonding technique, direct molecular bonding technique, SiO 2 A dielectric layer molecular bonding technology and a DVS-BCB bonding technology.
The direct molecular bonding technique generates H in the bonding process 2 And H 2 O, which causes bubbles to exist inside the bonding layer, thereby degrading bonding quality and yield. SiO 2 2 The dielectric layer molecular bonding technology can effectively solve the problem of generating secondary gas in the bonding process, improve the bonding quality and improve the coupling efficiency between the gain region and the silicon waveguide.
The technical scheme of the invention is as follows:
an apodized grating based high power silicon-based semiconductor laser comprising: the quantum well active region comprises a substrate, a buried oxide layer, a waveguide layer, an auxiliary bonding layer, a spacing layer, a cladding layer, a quantum well active region, a top cladding layer, an ohmic contact layer, a P-type electrode and an N-type electrode;
an apodization grating is etched in the waveguide layer along the cavity length direction of the resonant cavity;
the effective refractive index of the resonant cavity and the grating coupling coefficient are changed along the cavity length direction of the resonant cavity by modulating the transverse width of the apodized grating.
Further preferably, the effective refractive index of the resonant cavity and the grating coupling coefficient are changed along the cavity length direction of the resonant cavity by modulating the lateral width of the apodized grating, and the effective refractive indexes of the low refractive index part and the high refractive index part of the grating are selected by adjusting and selecting the appropriate lateral width of the grating
Thereby selecting the effective refractive index n of the grating eff And a grating coupling coefficient k;
d represents the duty cycle, λ 0 Is the bragg wavelength.
According to the optimization of the invention, the resonant cavity is sequentially divided into a first uniform area, an apodization area and a second uniform area from left to right, and the grating coupling coefficient and the effective refractive index in the first uniform area and the second uniform area are kept unchanged; in the toe-cut region, the grating coupling coefficient and the effective refractive index change linearly.
Further preferably, the effective refractive index of the first uniform region is n eff1 Coefficient of grating coupling k 1 (ii) a The effective refractive index of the second uniform region is n eff2 Coefficient of grating coupling k 2 (ii) a Apodized region grating coupling coefficient from k 1 To k 2 Linearly changing, effective refractive index from n eff1 To n eff2 A linear change;
let the lengths of the first uniform region, the apodized region and the second uniform region be l 1 、l 2 、l 3 Let z, 0 be the distance from a certain position of the apodization region to the leftmost end of the resonant cavity<z<l 1 +l 2 +l 3 Apodized region grating coupling coefficient distribution k (z) and effective refractive index distribution n eff (z) is represented by formula (I) and formula (II):
determination of optimal n by simulation eff1 、n eff2 、k 1 、k 2 The highest SMSR and highest output light power and a smooth optical field distribution are obtained for the output light.
Preferably, according to the present invention, the total length of the apodized grating along the cavity length direction of the resonant cavity is 300-1000 μm, the length of the first uniform region along the cavity length direction of the resonant cavity is 200-900 μm, the length of the apodized region along the cavity length direction of the resonant cavity is 5-50 μm, and the length of the second uniform region along the cavity length direction of the resonant cavity is 30-200 μm.
Preferably, according to the invention, the duty cycle of the apodized grating is between 0.4 and 0.6.
According to a preferred embodiment of the invention, the grating width of the apodized gratingW 1 0-2 μm, the grating width W of the apodized grating 2 0.3-7 μm; width W of grating 1 Refers to the width of the low refractive index portion of the grating; width W of grating 2 Refers to the width of the high index portion of the grating.
Further preferably, the total length of the apodized grating along the cavity length direction of the resonant cavity is 500 μm, the length of the first uniform region along the cavity length direction of the resonant cavity is 410 μm, the length of the apodized region along the cavity length direction of the resonant cavity is 20 μm, and the length of the second uniform region along the cavity length direction of the resonant cavity is 70 μm; the grating period of the apodized grating is 240.3nm, and the duty ratio of the apodized grating is 0.5; grating width W of apodized grating 1 Taking the grating width W of 0-2 μm apodized grating 2 Taking 0.3-7 μm.
According to the present invention, preferably, the waveguide layer has an apodized grating etched therein along the cavity length direction of the resonant cavity, and the apodized grating includes:
firstly, depositing a layer of photoetching mask on the surface of the waveguide layer, and photoetching to form a patterned structure; then, carrying out dry etching to form a first etching depth grating structure;
secondly, photoetching and dry etching are carried out in sequence to form a second etching depth grating structure;
and finally, photoetching and dry etching are sequentially carried out until the oxide layer is buried, and the strip waveguide is formed.
According to the invention, the material of the substrate is preferably Si; the buried oxide layer is made of SiO 2 The thickness is 0.5-3 μm; the waveguide layer is made of Si and has a thickness of 220-500 nm; the auxiliary bonding layer is made of SiO 2 The thickness is 0-300 nm; the material of the spacing layer is InP, and the thickness of the spacing layer is 10-200 nm; the material of the cladding is SiO 2 The thickness is 200-3000 nm; the quantum well active region is made of InAlGaAs or InGaAsP, the thickness is 300-600nm, and the width is 1.5-10 μm; the top cladding layer is made of InP, the thickness of the top cladding layer is 1.4-1.8 mu m, the width of the top end of the top cladding layer is 1.5-10 mu m, and the width of the bottom end of the top cladding layer is 1.5-9 mu m; the ohmic contact layer is made of InGaAs and has the thickness of 150 nm; the material of the P-type electrode is TiPtAu-Au or Ti/Al, and the thickness is 200-4000 nm; the N typeThe electrode is made of TiPtAu-Au or Ti/Al and has the thickness of 200-4000 nm.
Further preferably, the substrate has a thickness of 750 μm; the thickness of the buried oxide layer is 1000 nm; the thickness of the waveguide layer is 400 nm; the auxiliary bonding layer is 70nm thick; the thickness of the spacing layer is 150 nm; the thickness of the cladding is 2000 nm; the thickness of the quantum well active region is 400nm, the width of the quantum well active region is 7 microns, the quantum well active region comprises three well layers and four barrier layers, the well layers and the barrier layers are arranged in a crossed mode, the thickness of each well layer is 7nm, and the thickness of each barrier layer is 9 nm; the thickness of the top coating layer is 1.6 micrometers, the width of the top end is 4 micrometers, and the width of the bottom end is 2.5 micrometers; the thickness of the ohmic contact layer is 150 nm; the thickness of the P-type electrode is 2000 nm; the thickness of the N-type electrode is 2000 nm.
The invention has the beneficial effects that:
the invention integrates the advantages of high luminous efficiency of the III-V gain chip and high integration level and high transmission capacity of the SOI silicon optical chip. Meanwhile, through the design of the apodization grating, the photon density at two ends of the laser cavity has asymmetry, the output light power and the utilization efficiency are obviously improved, and the problem of low output light power/efficiency of the lambda/4 phase-shift laser is effectively solved while the stable single-mode output is ensured. Compared with a lambda/4 phase-shift laser, the resonant cavity based on the apodized grating has more gentle intra-cavity optical field distribution, thereby solving the influence of spatial hole burning of the lambda/4 phase-shift laser and obtaining better laser performance.
Drawings
FIG. 1 is a schematic structural diagram of an apodized grating-based high power silicon-based semiconductor laser of the present invention;
FIG. 2 is a schematic diagram of an apodized grating according to the present invention;
FIG. 3 is a schematic diagram of a lasing spectrum of an apodized grating-based high power silicon-based semiconductor laser according to the present invention;
FIG. 4 is a graph of normalized intracavity photon concentration;
fig. 5 is an LI curve diagram of the apodized grating-based high power silicon-based semiconductor laser of the present invention.
1. The quantum well active region comprises a substrate, 2, a buried oxide layer, 3, a waveguide layer, 4, an auxiliary bonding layer, 5, a spacing layer, 6, a cladding layer, 7, a quantum well active region, 8, a top cladding layer, 9, an ohmic contact layer, 10, a P-type electrode, 11 and an N-type electrode.
Detailed Description
The invention is further defined in the following, but not limited to, the figures and examples in the description.
Example 1
An apodized grating based high power silicon-based semiconductor laser, as shown in fig. 1, comprising: the device comprises a substrate 1, a buried oxide layer 2, a waveguide layer 3, an auxiliary bonding layer 4, a spacing layer 5, a cladding layer 6, a quantum well active region 7, a top cladding layer 8, an ohmic contact layer 9, a P-type electrode 10 and an N-type electrode 11;
an apodization grating is etched in the waveguide layer 3 along the cavity length direction of the resonant cavity; the method comprises the following steps: the apodization grating is processed by a standard silicon photo CMOS process, and generally comprises three steps of etching: firstly, depositing a layer of photoetching mask on the surface of a waveguide layer 3, and photoetching by using high-precision photoetching equipment to form a patterned structure; then, carrying out dry etching to form a first etching depth grating structure; secondly, photoetching and dry etching are sequentially carried out to form a second etching depth grating structure; and finally, photoetching and dry etching are sequentially carried out until the buried oxide layer 2 is etched, and the strip waveguide is formed.
The effective refractive index of the resonant cavity and the grating coupling coefficient are changed along the cavity length direction of the resonant cavity by modulating the transverse width of the apodized grating.
Example 2
The high-power silicon-based semiconductor laser based on the apodized grating in the embodiment 1 is characterized in that:
the effective refractive index of the resonant cavity and the grating coupling coefficient are changed along the cavity length direction of the resonant cavity by modulating the transverse width of the apodized grating, the effective refractive index of the waveguide mode is related to the waveguide size, and the effective refractive index of the waveguide mode under the specific waveguide size can be obtained by simulation of a finite difference method, so that the effective refractive indexes of the low refractive index part and the high refractive index part of the grating are selected by adjusting and selecting the proper transverse width of the grating
Thereby selecting the effective refractive index n of the grating as a whole eff And a grating coupling coefficient k;
d represents the duty cycle, λ 0 Is the bragg wavelength.
According to the invention, relative phase shift is introduced through the change of the effective refractive index, and the difference of the threshold gain between the fundamental modes at two sides of the stop band and the difference of the threshold gain between the fundamental mode and the high-order mode can be changed, so that the dual-mode degeneracy phenomenon is broken, and a preferred lasing mode is obtained. The apodization grating is adopted to realize the single-mode work of the laser, and compared with a lambda/4 phase-shift laser, the distribution of the optical field in the cavity is smoother, and the spatial hole burning effect is effectively reduced. The invention also designs the change of the grating coupling coefficient along the cavity length direction, can change the distribution of photon density and carrier density in the cavity, and makes the longitudinal distribution of the cavity become asymmetric, and makes the photon density near the output end larger, thereby improving the output light power of the laser.
The invention integrates the advantages of high luminous efficiency of III-V gain chip and high integration level and high transmission capacity of SOI silicon optical chip. Meanwhile, through the design of the apodization grating, the photon density at two ends of the laser cavity has asymmetry, the output light power and the utilization efficiency are obviously improved, and the problem of low output light power/efficiency of the lambda/4 phase-shift laser is effectively solved while the stable single-mode output is ensured. And secondly, compared with the lambda/4 phase-shift laser, the resonant cavity based on the apodized grating has more gentle intra-cavity optical field distribution, thereby solving the influence of spatial hole burning of the lambda/4 phase-shift laser and obtaining better laser performance.
Example 3
The high-power silicon-based semiconductor laser based on the apodized grating in the embodiment 1 is characterized in that:
as shown in fig. 2, the resonant cavity is sequentially divided into a first uniform region, an apodization region and a second uniform region from left to right, and the grating coupling coefficient and the effective refractive index in the first uniform region and the second uniform region are kept unchanged; by controlling the transverse width of the grating in the region, the transverse widths of the gratings are respectively kept consistent along the cavity length direction, so that the coupling coefficient and the effective refractive index of the grating are kept unchanged; in the toe-cut region, the grating coupling coefficient and the effective refractive index change linearly. The grating coupling coefficient and the effective refractive index are linearly changed along the cavity length direction by controlling the transverse width of the grating in the area, and the change of the specific width is determined by simulation.
Let the effective refractive index of the first uniform region be n eff1 Coefficient of grating coupling k 1 (ii) a The effective refractive index of the second uniform region is n eff2 Coefficient of grating coupling k 2 (ii) a Apodized region grating coupling coefficient from k 1 To k 2 Linearly varying, effective refractive index from n eff1 To n eff2 A linear change;
suppose the lengths of the first uniform region, the apodized region, and the second uniform region are l 1 、l 2 、l 3 Let z, 0 be the distance from a certain position of the apodization region to the leftmost end of the resonant cavity<z<l 1 +l 2 +l 3 Apodized region grating coupling coefficient distribution k (z) and effective refractive index distribution n eff (z) is represented by formula (I) and formula (II):
determination of optimal n by simulation eff1 、n eff2 、k 1 、k 2 The highest SMSR and highest output light power and a smooth optical field distribution are obtained for the output light. The simulation results are shown in fig. 3, 4 and 5.
The apodization grating of the embodiment can introduce refractive index change in the cavity to generate equivalent phase shift, thereby breaking the dual-mode degeneracy phenomenon existing in the DFB laser and achieving the purpose of single-mode output of the laser. The laser output spectrum is shown in fig. 3.
The optical field distribution in the resonant cavity is not uniform due to the non-uniform distribution of the grating coupling coefficient. When the grating coupling coefficient in the toe-cutting area is larger than that in the first uniform area, more photons in the cavity are distributed at the left end of the resonant cavity, as shown in fig. 4, so that the optical power obtained at the output end of the resonant cavity is increased, and the utilization efficiency of output light is improved. Meanwhile, as can be seen from fig. 4, compared with the traditional λ/4 phase-shifted laser, the resonant cavity structure designed based on the apodized grating has a more gradual optical field distribution in the cavity, so that the spatial hole burning effect can be effectively inhibited.
The LI curve of the laser of this embodiment is shown in fig. 5, and the optical output power of this embodiment is significantly improved compared with the same case of the equal threshold λ/4 phase-shifted laser.
Example 4
The high-power silicon-based semiconductor laser based on the apodized grating in the embodiment 1 is characterized in that:
the total length of the apodization grating along the cavity length direction of the resonant cavity is 300-1000 mu m, the length of the first uniform region along the cavity length direction of the resonant cavity is 200-900 mu m, the length of the apodization region along the cavity length direction of the resonant cavity is 5-50 mu m, and the length of the second uniform region along the cavity length direction of the resonant cavity is 30-200 mu m.
Optimum laser performance, such as higher output power and good single mode characteristics, can be obtained from the above arrangement of cavity length and region length.
The grating period of the apodization grating is designed according to the lasing wavelength of a laser, the typical optical communication wavelength is about 1310nm, and the corresponding period is 201-207 nm; the laser has a lasing wavelength around 1550nm, a corresponding period of 238-246nm, and a duty cycle of the apodized grating of 0.4-0.6.
Grating width W of apodized grating 1 0-2 μm, the grating width W of the apodized grating 2 0.3-7 μm; width W of grating 1 Refers to the width of the low refractive index portion of the grating; width W of grating 2 Refers to the width of the high index portion of the grating.
Each of the gratingsOne period is composed of two parts including high-refractivity part and low-refractivity part, and in the present invention, the high-refractivity part and the low-refractivity part are distinguished by different grating widths, and their widths are respectively W 2 、W 1 . The determined grating size corresponds to the determined effective index, and thus the effective index and the grating coupling coefficient can be controlled by controlling the grating width.
The substrate 1 is made of Si; the buried oxide layer 2 is made of SiO 2 The thickness is 0.5-3 μm; the waveguide layer 3 is made of Si and has a thickness of 220-500 nm; in the waveguide layer 3, the selection of the lasing mode is realized through the apodization grating. The auxiliary bonding layer 4 is made of SiO 2 The thickness is 0-300 nm; the III-V semiconductor material is adhered to the waveguide layer 3 by a silicon dioxide dielectric layer molecular bonding technique. The material of the spacing layer 5 is InP, and the thickness is 10-200 nm; the cladding 6 is made of SiO 2 The thickness is 200-3000 nm; the quantum well active region 7 is made of InAlGaAs or InGaAsP, the thickness is 300-600nm, and the width is 1.5-10 μm; the quantum well active region 7 provides optical gain; the top cladding layer 8 is made of InP, the thickness is 1.4-1.8 μm, the width of the top end is 1.5-10 μm, and the width of the bottom end is 1.5-9 μm; the ohmic contact layer 9 is made of InGaAs and has a thickness of 150 nm; the P-type electrode 10 is made of TiPtAu-Au or Ti/Al and has a thickness of 200-4000 nm; the N-type electrode 11 is made of TiPtAu-Au or Ti/Al and has a thickness of 200-4000 nm.
Example 5
The high-power silicon-based semiconductor laser based on the apodized grating in the embodiment 1 is characterized in that:
the total length of the apodization grating along the cavity length direction of the resonant cavity is 500 mu m, the length of the first uniform region along the cavity length direction of the resonant cavity is 410 mu m, the length of the apodization region along the cavity length direction of the resonant cavity is 20 mu m, and the length of the second uniform region along the cavity length direction of the resonant cavity is 70 mu m; the grating period of the apodized grating is 240.3nm, and the duty ratio of the apodized grating is 0.5; grating width W of apodized grating 1 Taking the grating width W of 0-2 μm apodized grating 2 Taking 0.3-7 μm.
The thickness of the substrate 1 is 750 μm; the thickness of the buried oxide layer 2 is 1000 nm; the thickness of the waveguide layer 3 is 400 nm; the auxiliary bonding layer 4 has a thickness of 70 nm; the thickness of the spacer layer 5 is 150 nm; the thickness of the cladding 6 is 2000 nm; the thickness of the quantum well active region 7 is 400nm, the width is 7 μm, the quantum well active region 7 comprises three well layers and four barrier layers, the well layers and the barrier layers are arranged in a crossed mode, the thickness of each well layer is 7nm, and the thickness of each barrier layer is 9 nm; the thickness of the top coating layer 8 is 1.6 μm, the width of the top end is 4 μm, and the width of the bottom end is 2.5 μm; the thickness of the ohmic contact layer 9 is 150 nm; the thickness of the P-type electrode 10 is 2000 nm; the thickness of the N-type electrode 11 was 2000 nm.
Claims (10)
1. A high power silicon-based semiconductor laser based on apodized grating, comprising: the quantum well active region comprises a substrate, a buried oxide layer, a waveguide layer, an auxiliary bonding layer, a spacing layer, a cladding layer, a quantum well active region, a top cladding layer, an ohmic contact layer, a P-type electrode and an N-type electrode; an apodization grating is etched in the waveguide layer along the cavity length direction of the resonant cavity; the effective refractive index of the resonant cavity and the grating coupling coefficient are changed along the cavity length direction of the resonant cavity by modulating the transverse width of the apodized grating.
2. The high power silicon-based semiconductor laser device as claimed in claim 1, wherein the effective refractive index of the low refractive index portion and the high refractive index portion of the grating is selected by adjusting and selecting the proper lateral width of the grating by modulating the lateral width of the apodized grating so that the effective refractive index of the resonant cavity and the grating coupling coefficient vary along the cavity length direction of the resonant cavity
Thereby selecting the effective refractive index n of the grating eff And a grating coupling coefficient k;
d represents the duty cycle, λ 0 Is the bragg wavelength.
3. The high-power silicon-based semiconductor laser based on the apodized grating according to claim 1, wherein the resonant cavity is sequentially divided into a first uniform region, an apodized region and a second uniform region from left to right, and the grating coupling coefficient and the effective refractive index are kept unchanged in the first uniform region and the second uniform region; in the toe-cut region, the grating coupling coefficient and the effective refractive index change linearly.
4. The high power silicon-based semiconductor laser based on apodized grating according to claim 3, wherein the effective refractive index of the first uniform region is set to n eff1 Coefficient of grating coupling k 1 (ii) a The effective refractive index of the second uniform region is n eff2 Coefficient of grating coupling k 2 (ii) a Apodized region grating coupling coefficient from k 1 To k 2 Linearly changing, effective refractive index from n eff1 To n eff2 A linear change;
let the lengths of the first uniform region, the apodized region and the second uniform region be l 1 、l 2 、l 3 Let z be the distance from a certain position of the apodization region to the leftmost end of the resonant cavity, where 0 < z < l 1 +l 2 +l 3 Apodized region grating coupling coefficient distribution k (z) and effective refractive index distribution n eff (z) is represented by formula (I) and formula (II):
determination of optimal n by simulation eff1 、n eff2 、k 1 、k 2 The optimal SMSR and the highest output light power and smooth optical field distribution of the output light are obtained.
5. The high power Si-based semiconductor laser as claimed in claim 3, wherein the total length of the apodized grating along the cavity length direction of the resonant cavity is 300-1000 μm, the length of the first uniform region along the cavity length direction of the resonant cavity is 200-900 μm, the length of the apodized region along the cavity length direction of the resonant cavity is 5-50 μm, and the length of the second uniform region along the cavity length direction of the resonant cavity is 30-200 μm.
6. The high power silicon-based semiconductor laser based on an apodized grating according to claim 1, wherein the duty cycle of the apodized grating is 0.4-0.6.
7. The high power silicon-based semiconductor laser based on an apodized grating according to claim 1, wherein the grating width W of the apodized grating 1 0-2 μm, the grating width W of the apodized grating 2 0.3-7 μm; width W of grating 1 Refers to the width of the low refractive index portion of the grating; width W of grating 2 Refers to the width of the high index portion of the grating.
8. The high power silicon-based semiconductor laser based on the apodized grating according to claim 1, wherein the total length of the apodized grating along the cavity length direction of the resonant cavity is 500 μm, the length of the first uniform region along the cavity length direction of the resonant cavity is 410 μm, the length of the apodized region along the cavity length direction of the resonant cavity is 20 μm, and the length of the second uniform region along the cavity length direction of the resonant cavity is 70 μm; the grating period of the apodized grating is 240.3nm, and the duty ratio of the apodized grating is 0.5; grating width W of apodized grating 1 Taking the grating width W of 0-2 μm apodized grating 2 Taking 0.3-7 μm.
9. The high power silicon-based semiconductor laser based on the apodized grating according to claim 1, wherein the material of the substrate is Si; the buried oxide layer is made of SiO 2 The thickness is 0.5-3 μm; the waveguide layer is made of Si,the thickness is 220-500 nm; the auxiliary bonding layer is made of SiO 2 The thickness is 0-300 nm; the material of the spacing layer is InP, and the thickness of the spacing layer is 10-200 nm; the material of the cladding is SiO 2 The thickness is 200-3000 nm; the quantum well active region is made of InAlGaAs or InGaAsP, the thickness is 300-600nm, and the width is 1.5-10 μm; the top cladding layer is made of InP, the thickness of the top cladding layer is 1.4-1.8 mu m, the width of the top cladding layer is 1.5-10 mu m, and the width of the bottom cladding layer is 1.5-9 mu m; the ohmic contact layer is made of InGaAs and has the thickness of 150 nm; the material of the P-type electrode is TiPtAu-Au or Ti/Al, and the thickness is 200-4000 nm; the N-type electrode is made of TiPtAu-Au or Ti/Al and has a thickness of 200-4000 nm.
10. An apodized grating based high power silicon based semiconductor laser according to any of claims 1-9, wherein the substrate has a thickness of 750 μm; the thickness of the buried oxide layer is 1000 nm; the thickness of the waveguide layer is 400 nm; the auxiliary bonding layer is 70nm thick; the thickness of the spacing layer is 150 nm; the thickness of the cladding is 2000 nm; the thickness of the quantum well active region is 400nm, the width of the quantum well active region is 7 microns, the quantum well active region comprises three well layers and four barrier layers, the well layers and the barrier layers are arranged in a crossed mode, the thickness of each well layer is 7nm, and the thickness of each barrier layer is 9 nm; the thickness of the top coating layer is 1.6 micrometers, the width of the top end is 4 micrometers, and the width of the bottom end is 2.5 micrometers; the thickness of the ohmic contact layer is 150 nm; the thickness of the P-type electrode is 2000 nm; the thickness of the N-type electrode is 2000 nm.
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